Kingston High School Chemistry First Semester Final Exam Review Andrew Carr

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1 Kingston High School Chemistry First Semester Final Exam Review Andrew Carr READ THIS! We ve covered five fundamental chemistry topics so far this year: 1. Atomic structure, scale, & the four universal forces, 2. Phases of matter & kinetic molecular theory, 3. Light & electron structure, 4. Periodic trends, and 5. Chemical bonds and naming compounds & acids. We framed them using a few puzzling phenomena that hopefully put these concepts into context: the drinking bird, color and the stars, and reactivity of metals. Due to time constraints, questions about the drinking bird will not be included on this final exam. This final exam review is broken into two sections: Key Points, a summary outline of those five aforementioned topics, and Practice Questions, a series of exam like questions taken from this semesters assessments. Directions: 1) Read through the Key Points section first, then work on the Practice Questions, 2) spend at least one hour per day outside of class studying for the final exam using this review as your guide (more time if you are failing or close to failing this class), 3) use the links to Video Resources if you don t understand a topic, 4) get together with classmates to study; evidence shows discussion is an effective way to learn, 5) contact me if you have any questions (see contact info at the top of this page), and I ll get back to you ASAP. KEY POINTS I. Topic 1: Atomic structure/scale/four universal forces a. Atomic Structure i. Atoms: the smallest unit into which matter can be divided without the release of electrically charged particles. They are made up of three subatomic particles 1 : 1. Protons (p + ) a. Positive charge, found in the nucleus, its mass equals 1 Figure 1a atomic mass unit (amu)., attracted to electrons 2. Electron (e - ) a. Negatively charged, found in space outside the nucleus, so small it has little to no mass, attracted to protons, can be lost or gained to form ions, responsible for chemical bonding between atoms 3. Neutron (n 0 ) a. No charge (i.e. neutral), found in nucleus with p +, also has mass of 1 amu, doesn t attract or repel protons & electrons, stabilizes the nucleus (i.e. keeps the nucleus together, otherwise p + repel each other), number of n 0 is not always equal to the number of protons! 4. The atomic model (see figure 1a) a. Video resource WATCH THIS ii. Compounds are groups of two or more atoms joined together by chemical bonds iii. Atomic number & identity, mass, & charged atoms (see figure 1b) Figure 1b 1 These three basic particles can be broken down into even smaller particles such as quarks, leptons, bosons, neutrinos, alpha (α) particles, etc. but the complexity of these sub-sub-atomic particles is beyond the scope of this course.

2 a. Atomic number equals number of protons in the nucleus i. Gives an element its identity (e.g. 4 p + = beryllium, 11 p + = sodium, etc.) 1. Element-fundamental form of matter that cannot be broken down into simpler atoms b. Atom mass = the number of n 0 + the number of p + i. Can also be used to determine approximate number of neutrons (Atomic mass number of protons = number of neutrons) iv. Charge of an atom 1. Ion- an atom that has lost or gained an electron a. Oxidation number = the number of electrons an element can potentially gain or lose 2. Neutral atoms have no charge, so its number of electrons = its number of protons v. Calculating mass, atomic number, and charge of an atom 1. Video resource WATCH THIS b. Scale i. Atoms are incredibly small, but make up everything in the universe. It s important to easily move between these different frames of reference in order to explain and understand chemistry: 1. Molecular-not directly observable, too small to be seen 2. Microscopic- observable only under magnification 3. Macroscopic-observable with our eyes ii. We use scientific notation (see figure 1c) to quantify Figure 1c these different scales and easily work between very small and very large quantities 1. Video resource WATCH THIS c. Four Universal Forces (see figure below) i. Listed in order from strongest to weakest ii. Video resource WATCH THIS II. Topic 2: Phases of Matter & Kinetic Molecular Theory a. Atoms and compounds are constantly moving b. The phase of matter of a compound depends several factors: i. Its kinetic energy (energy of motion) 1. Temperature is a measure of the average Figure 2a

3 kinetic energy of a system. a. There s really no such thing as hot and cold in chemistry, only fast or slow moving atoms & molecules ii. Its total atomic mass, iii. How tightly compounds are held together (see figure 2a) 1. Bonds can be intramolecular (forces that hold atoms together in a compound) or intermolecular (forces hold compounds together) iv. The pressure of the system (i.e. how tightly atoms are pressed together in a compound) Figure 2b 1. Pressure is a measure of collisions of atoms/compounds against its container v. Video resource WATCH THIS vi. There are three phases of matter 2 1. The phases are illustrated in figure 2b to the right 2. Compounds have their own unique physical properties, which include melting and boiling points a. Phase diagrams (see figure 2c below) display the relationship between phase of matter, pressure, and temperature Figure 2c Figure 2d 3. Qualitative facts about each phase are summarized in Table 2 below Table 2 State of Matter Solid Liquid Gas Can you push through it? Can molecules move around or are they stuck in place? Can You Compress it? No Stuck in place No Yes The move around, but are still stuck together No Yes Move around Yes Is there a lot of space between the molecules or very little space? Will it retain its shape or take on shape of the container? Does it maintain its volume or assume the volume of its container? Very little space Retain its shape Maintains its volume There is some Take on shape of Assumes volume space between container of its container molecules A lot of space Take on shape container Assumes shape of container III. Topic 3-Light and electron structure a. Electromagnetic radiation (EMR) is made when an atom absorbs energy i. This energy causes subatomic particles in the atoms to move 1. When the energy is released, it propagates (moves) outward from its source in all directions as an electromagnetic waves 2 This is for science we nerds only. You won t be tested on any of this footnote, so feel free to skip if you want to. If you really want to get technical, there are two additional phases of matter that include plasma, matter consisting of highly charged particles with extremely high kinetic energy. Plasma is not found commonly on earth but is plentiful throughout the universe. The other are Bose-Einstein condensates, which occurs when atoms approach a few degrees of absolute zero K ( C/ F); in this state groups of atoms come to an almost complete stop, clump together to occupy the same energy state, and behave as if a single atom. It was theorized by Satyendra Nath Bose and Albert Einstein almost 100 years ago, but wasn t fully reached in the lab until the 1990s. It s been described as being able to observe the quantum state of matter on the macroscopic scale.

4 2. Depending on the kind of atom(s), the type of subatomic particle(s) involved, and the amount of energy absorbed/released, the EMR can take on one of seven forms a. These forms are shown on the electromagnetic spectrum (figure 3a) below (ex. Radio waves, microwaves, infrared, etc.) Figure 3a b. The frequency of the wave is proportional to its energy and inversely proportional to its wavelength b. Visible light (Video resource WATCH THIS i. Produced when the absorbed energy causes one or more electrons to change their locale (to an excited state) within the electron shell of an atom. 1. When electrons return to original position (called the ground state), EMR is emitted in the form of visible light. 2. The wavelength/energy of the light color is proportional to the distance the electron(s) moves back to the ground state (see figure 3b) a. ROY G BIV = red orange yellow blue indigo violet) red has the lowest energy (frequency)/longest wavelength, violet is on the opposite end of the spectrum b. EXTREMELY IMPORTANT HINT WHEN STUDYING BLACK AND WHITE DIAGRAMS Figure 3b DESCRIBING COLOR LIGHT WAVES: pay attention to the wavelength!! Remember: Violet light = short wavelength = relatively high frequency = relatively high energy. Red light is the opposite. ii. Spectral fingerprints (Video Resource WATCH THIS 1. Different elements produced different color lights when energized (e.g. heated) a. When viewed through a spectroscope (prism), these colors appear as lines (spectral lines) associated with specific wavelengths on the spectum (i.e. violets ~400 nm, reds ~700 nm) b. Spectral lines can be used to identify the specific elements that make up compounds i. Just like human fingerprints, these spectral lines can be compared to previously collected "fingerprints" of atoms and molecules and are thus used to identify the atomic and molecular components of stars and planets which would otherwise be impossible to know iii. Red shift, the Doppler Effect, and Moving Galaxies 1. Light spectra can also be used to analyze the movement of galaxies 2. Note in Figure 3c a. the emission spectra shifts to higher frequencies (i.e. higher energy like blue light) as the galaxy move towards the observer, but it b. shifts to lower frequencies (i.e. lower energy red light) as it moves away from the observer

5 Figure 3c- Red Shift 3. Video Resource WATCH THIS 4. Figure 3d illustrates the Doppler effect Figure 3d IV. Topic 4 Periodic Trends (Video Resource WATCH THIS a. The periodic table is an arrangement of the chemical elements, ordered by their atomic number, electron configuration, and recurring chemical properties. b. This ordering shows periodic trends, such as elements with similar behavior in the same column. c. The key to understanding how the table is organized, and thus the periodic trends, is Coulombic attraction. i. Coulombic attraction is a principal concept in science with its roots grounded in electromagnetic forces 1. It s the measure of the force of attraction (or repulsion) between charged particles, like protons and electrons 2. The two variables that affect the magnitude of Coulombic attraction are: a. The number of particles b. Distance between particles i. Note that Figure 4a illustrates Coulombic attraction is affected most Figure 4a

6 by distance! d. Electron configurations (see Figure 4b) i. Electrons are arranged around the nucleus according to a series of principles best explained by the quantum mechanics, which is a subject beyond the scope of this course. ii. Electrons are found in energy levels (a.k.a. electron shells) 1. The number of electron shells (a.k.a. energy levels) increase as one moves down a group a. They correspond to the period (row) number iii. The outermost electron shell is called the valence shell 1. Electrons in the valence shell are called valence electrons a. Because they are the furthest from the nucleus, they experience the least amount of Coulombic attraction and are the electrons most likely to be involved in the chemical bonding process with other atoms 2. For main group elements, the group number corresponds to the number of valence electrons Figure 4b Number of Valence Electrons Number of Electron Shells e. Atomic Radius i. The distance between the nucleus and valence electron(s) 1. Increases as one moves down each group 2. Decreases from left to right across each period a. Number of electron shells don t increase, but number of protons and electrons DO increase causing the Coulombic force to increase and pull these subatomic particles closer together f. Ionization Energy i. The energy required to remove an electron 1. Decreases as one moves down each group; atomic radius increases and Coulombic attraction decreases 2. Increases from left to right across a period because Coulombic attraction increases due to increased number of particles and smaller atomic radius g. Electronegativity i. The measure of attraction the nucleus of one atom has for the electron(s) of another 1. Decreases as one moves down each group; atomic radius increases and Coulombic attraction decreases 2. Increases from left to right across a period because Coulombic attraction increases due to

7 increased number of particles and smaller atomic radius V. Topic V- Chemical Bonds a. A lasting attraction between atoms that enables the formation of chemical compounds b. Types: i. Ionic compounds 1. A chemical bond in which positively charged cations transfer electrons to negatively charged anions a. Ion- an atom with an electric charge due to an uneven number of electrons compared to protons i. Positive ions have LOST electrons and gained a positive charge 1. Metals 2. Charge number will equal its number of valence electrons ii. Negative ions have GAINED electrons and gained a negative charge 1. Non-metals Cations are pawsitive 2. Charge number will equal the number of valence electrons it needs to gain in order to assume the electron configuration of its closest Noble Gas a. Octet Rule- atoms form ions to assume the electron configuration of its closest Noble Gas 2. Difference in electronegativity between atoms is 1.7 Can be quantified ii. Covalent (Molecular) Compounds 1. A chemical bond between nonmetals when they share electrons 2. Polar covalent a. Uneven sharing of electrons creates molecules with charged poles (like a battery or magnet) i. Creates strong intermolecular forces between other polar molecules b. Electronegativity difference between ~0.4 and ~ Non-polar covalent a. Even sharing of electrons i. Weak intermolecular forces between other nonpolar molecules b. Electronegativity difference ~0.4 iii. Acids 1. Covalently bonded molecules that produce ions when put into water. a. One of the ions produced is always H +, which immediately combines with a water molecule (H 2O) to form the hydronium ion (H 3O + ). i. The H 3O + hydronium ion is what defines acidic properties (ph level) of a substance iv. Naming compounds and acids 1. Ionic & molecular compounds, along with acids, all use different naming conventions to write the chemical formula for the name, and vice versa. 2. Refer to previous class notes or the flowcharts on the next two pages to write the name or formula.

8 Practice Questions Topic 1 For questions 1-9, match the description with the correct sub atomic particle(s) a. Electron b. Proton c. Neutron d. Proton & neutron e. Proton & electron 1. Responsible for stabilizing the nucleus 2. Can be transferred or shared; responsible for chemical bonding between atoms 3. Has a positive charge 4. Located in the nucleus 5. Makes up most of the mass of an atom 6. Does not have a charge; i.e. has a neutral charge 7. Attracts and holds electrons to the atom 8. Creates Coulombic attraction 9. Has a tiny mass that is practically zero 10. How many protons does an atom of beryllium have? 11. How many neutrons does an atom of nitrogen have? 12. How many neutrons are in an atom of cesium? 13. How many electrons are there in a neutral atom of sodium? 14. How many electrons are there in a sodium ion? 15. How many electrons are in a neutral iodine atom? 16. How many electrons are there in a iodide ion? 17. Iron has two oxidation numbers, 2 and 3. How many electrons are in an ion of iron (II) and in an iron (III) ion? 18. Which of the four universal forces For questions 10-22, match the universal force with its role. 19. Hold matter together a. Strong force 20. Holds the atom together b. Electromagnetic force 21. Holds the nucleus together c. Weak force 22. Hold particles in the nucleus together d. Gravitational force 23. Rank those forces from strongest to weakest 24. Write the number 2,600,000,000 in scientific notation 25. Write the number in scientific notation Topic 2 questions 26. Forces that hold atoms together are molecular forces 27. Forces that hold compounds together are molecular forces Use the table to the right to answer questions 28 & Which list below correctly ranks the molecules from lowest to highest boiling points? a. H 2O N 2 O 2 He b. N 2 H 2O He O 2 c. He H 2O N 2 O 2 d. He N 2 O 2 H 2O 29. Which list below correctly ranks the molecules from weakest to strongest intermolecular forces? a. H2O N2 O2 He c. He H2O N2 O2 b. N2 H2O He O2 d. He N2 O2 H2O 30. In order to freeze into ice, the molecules that make up water have to: a. get hotter c. speed up b. get colder d. slow down

9 Use the phase diagram for CO2 to answer the following questions 31 to 34: 31. To change carbon dioxide from a liquid to a gas you would need to. a. Increase the temperature and/or decrease the pressure b. Decrease the temperature and/or increase the pressure c. Decrease both the temperature and pressure d. Increase both the temperature and the pressure 32. Increasing the pressure around a liquid will a. increase the boiling point of the liquid. b. decrease the boiling point of the liquid. c. not affect the boiling point of the liquid 33. To change carbon dioxide from a liquid to a solid you would need to (hint: make sure you look closely at Figure 2 when choosing your answer). a. Increase the temperature and/or decrease the pressure b. Decrease the temperature and/or increase the pressure c. Decrease both the temperature and pressure d. Increase both the temperature and the pressure 34. Increasing the temperature of carbon dioxide from -100 C to -40 C at 1 atm of pressure would change it from a solid to a vapor. This process is known as a. Freezing b. Melting c. Condensation d. Sublimation Topic 3 questions Figure 1 depicts energy levels in an atom of an unknown element that has been heated, and produced green, indigo, red, yellow, and violet color emissions. The direction of the arrow indicates which direction the electron moves. 35. Which arrow represents the electron gaining energy? Figure 1 9

10 36. Which arrow represents the transition that produced a green photon? 37. Which arrow represents the transition that produced an indigo photon? 38. Which arrow represents the transition that produced a red photon? 39. Which arrow represents the transition that produced a yellow photon? 40. Which arrow represents the transition that produced a violet photon? Use Figure 3 to answer question Which spectral lines are showing blue shift and which ones are showing red shift? Topic 4 questions 42. Summarize how the periodic trends of atomic radius, electronegativity, and ionization energy change as you move down a group and across a period. A complete answer will summarize how each trend relates to Coulombic attraction. 10

11 43. What is an ion? 44. What type of ions do metals form? What type of ions do non-metals form? 45. How many valence electrons and electron shells do each of the following elements have: a. Helium b. Chlorine c. Sodium d. Calcium e. Sulfur 46. Pick two different elements on the periodic table, and determine based on their positions, which one has the higher ionization energy and larger atomic radius. Topic Summarize the similarities and differences between ionic and covalent bonds. 48. What is the octet rule, and how can it be used to determine the number of electrons an atom will gain or lose when it becomes an ion? 49. Be sure to complete the Naming Compounds and Acids worksheet to practice naming compounds and writing their formula. 11